NEW YORK - Denis Ryjenko, 35, and his girlfriend, Natella Croussouloudis, 42, were arrested Sept. 3 as they tried to unload a small masterpiece, "Himalayas," by the prolific early 20th-century Russian artist Nicholas Roerich and valued at $125,000. One of them even told the "buyer," an undercover cop, that the painting was "hot." A second painting stolen from Nicholas Roerich Museum  -- titled "Talung Monastery" and worth $70,000 -- was mysteriously returned to museum by mail on Aug. 14.